internal/rosa: create metadata alongside artifact

This enables deferring evaluation of azalea-based packages and fixes the longstanding quirk of version being disjoint from other metadata.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/libpsl.go

@@ -25,9 +25,7 @@ test_disable 'int main(){return 0;}' tests/test-is-public-builtin.c
 	), version
 }
 func init() {
-	native.MustRegister(&Artifact{
-		f: Toolchain.newLibpsl,
-
+	native.mustRegister(Toolchain.newLibpsl, &Metadata{
 		Name:        "libpsl",
 		Description: "provides functions to work with the Mozilla Public Suffix List",
 		Website:     "https://rockdaboot.github.io/libpsl/",